This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. For understanding the electron transfer function and the detailed perturbation of the redox potential potentially afftected by the pKa of the two nearby histidine residues. We need to determine the pKa of the two histidines. Since the oxidized form works have been done by Jo, I would like to follow the reduced form works to see if there is any difference in the reduced form.